Generally, the widely-used peripheral input device of a computer system includes for example a mouse, a keyboard, a trackball, or the like. Via the keyboard, characters or symbols can be directly inputted into the computer system. As a consequence, most users and most manufacturers of input devices pay attention to the development of keyboards. As known, a keyboard with scissors-type connecting elements is one of the widely-used keyboards.
Hereinafter, a key structure with a scissors-type connecting element of a conventional keyboard will be illustrated with reference to FIG. 1. FIG. 1 is a schematic side cross-sectional view illustrating a conventional key structure. As shown in FIG. 1, the conventional key structure 1 comprises a keycap 11, a scissors-type connecting element 12, a rubbery elastomer 13, a membrane switch circuit member 14 and a base 15. The keycap 11, the scissors-type connecting element 12, the rubbery elastomer 13 and the membrane switch circuit member 14 are supported by the base 15. The scissors-type connecting element 12 is used for connecting the base 15 and the keycap 11.
The membrane switch circuit member 14 comprises plural key intersections (not shown). When one of the plural key intersections is triggered, a corresponding key signal is generated. The rubbery elastomer 13 is disposed on the membrane switch circuit member 14. Each rubbery elastomer 13 is aligned with a corresponding key intersection. When the rubbery elastomer 13 is depressed, the rubbery elastomer 13 is subjected to deformation to push the corresponding key intersection of the membrane switch circuit member 14. Consequently, the corresponding key signal is generated.
The scissors-type connecting element 12 is arranged between the base 15 and the keycap 11, and the base 15 and the keycap 11 are connected with each other through the scissors-type connecting element 12. The scissors-type connecting element 12 comprises a first frame 121 and a second frame 122. A first end of the first frame 121 is connected with the keycap 11. A second end of the first frame 121 is connected with the base 15. The rubbery elastomer 13 is enclosed by the scissors-type connecting element 12. Moreover, the first frame 121 comprises a first keycap post 1211 and a first base post 1212. The first frame 121 is connected with the keycap 11 through the first keycap post 1211. The first frame 121 is connected with the base 15 through the first base post 1212. The second frame 122 is combined with the first frame 121. A first end of the second frame 122 is connected with the base 15. A second end of the second frame 122 is connected with the keycap 11. Moreover, the second frame 122 comprises a second keycap post 1221 and a second base post 1222. The second frame 122 is connected with the keycap 11 through the second keycap post 1221. The second frame 122 is connected with the base 15 through the second base post 1222.
The operations of the conventional key structure 1 in response to the depressing action of the user will be illustrated as follows. Please refer to FIG. 1 again. When the keycap 11 is depressed, the keycap 11 is moved downwardly to push the scissors-type connecting element 12 in response to the depressing force. As the keycap 11 is moved downwardly relative to the base 15, the keycap 11 pushes the corresponding rubbery elastomer 13. At the same time, the rubbery elastomer 13 is subjected to deformation to push the membrane switch circuit member 14 and trigger the corresponding key intersection of the membrane switch circuit member 14. Consequently, the membrane switch circuit member 14 generates a corresponding key signal. When the keycap 11 is no longer depressed by the user, no external force is applied to the keycap 11 and the rubbery elastomer 13 is no longer pushed by the keycap 11. In response to the elasticity of the rubbery elastomer 13, the rubbery elastomer 13 is restored to its original shape to provide an upward elastic restoring force. Consequently, the keycap 11 is returned to its original position where it is not depressed.
In addition to the above keyboard with scissors-type connecting elements, another conventional keyboard with a mechanical key structure is introduced into the market. FIG. 2 is a schematic side cross-sectional view illustrating a conventional mechanical key structure. As shown in FIG. 2, the conventional mechanical key structure 2 comprises a keycap 21, a scissors-type connecting element 22, a mechanical triggering switch 23, a circuit board 24 and a base 25. The base 25 is connected with the keycap 21 through the scissors-type connecting element 22. The circuit board 24 is disposed under the base 25. The triggering switch 23 is supported by the circuit board 24. In addition, the circuit board 24 is electrically connected with the mechanical triggering switch 23. The mechanical triggering switch 23 is penetrated through the base 25 and the scissors-type connecting element 22, and contacted with the keycap 21. After the above components are combined with each other, the key structure 2 is assembled. The components of the key structure 2 from top to bottom include the keycap 21, the scissors-type connecting element 22, the base 25 and the circuit board 24 sequentially. The mechanical triggering switch 23 is arranged between the keycap 21 and the circuit board 24. In comparison with the key structure 1, the key structure 2 comprises the mechanical triggering switch 23 in replace of the rubbery elastomer 13 and the membrane switch circuit member 14.
When the mechanical triggering switch 23 is triggered by the keycap 21, a click sound is generated. Due to the click sound, the user can feel the depressing feedback. Consequently, the mechanical triggering switch 23 is favored by many users. However, for resulting in normal operation of the mechanical triggering switch 23, the circuit board 24 of the mechanical key structure 2 must be thicker than the membrane switch circuit member 14. Moreover, the mechanical triggering switch 23 is thicker than the rubbery elastomer 13. Consequently, the thickness of the conventional mechanical key structure 2 is larger than the thickness of the conventional key structure 1. Moreover, the inner portion of the mechanical triggering switch 23 comprises the components made of a metallic material and the components made of a plastic material. Consequently, when the keycap 21 is depressed, the metallic material and the plastic material in the mechanical triggering switch 23 may collide with each other. Under this circumstance, the conventional mechanical key structure 2 give a stiff feel to the user.
Therefore, there is a need of providing a key structure capable of providing a feedback feel and having enhanced tactile feel.